Apparatus for surface hardening the teeth of double helical gears



H. HOLLER 2,

NG THE TEETH DOUBLE HELICAL GEARS March 28, 1939.

APPARATUS FOR SURFACE HARDENI Filed Jan. 23, 1936 E INVENTOZ: BY I i@% am, QAfia ATTORNEYS.

Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR SURFACE HARDENIN G THE TEETH F DOUBLE HELICAL GEARS many Application fanuary 23, 1936, Serial No. 60,527 In Germany January 23, 1935 3 Claims. I (01. 266-) The present invention relates to an apparatus for surface hardening the teeth of double helical gears.

Surface hardening of the teeth of double helical 5 gears by means of the blow-pipe flame can be carried out by either of two known methods.

In one method the tooth to be treated is hardened in two sections, for instance once from the one outer edge towards the middle of the tooth and then from the middle to the other outer edge. In this case the gear wheel is stationary, while the burner is moved along the tooth flank which in this case has to be adjusted every time parallel to the direction, of motion of the burner.

As soon as the burner has arrived at the middle of the tooth, the whole toothed wheel must be reversed. In the other method the tooth flank to be hardened is passed in one stroke along the blow-pipe flame; the burner is, in this case stationary. The constant distance between the flame and the flank of the tooth which is required in this case is maintained by suitable means.

Both methods involve drawbacks. In the firstnamed method one has to put up with the inconvenience that in the summit of the tooth a soft place is produced this being due to the fact that the top of the one side of the tooth which is adjacent to the summit and has already been quenched, is heated again on a certain length when the burner is placed on the other side of the tooth in order to heat it. In the other method named above the gear wheel must be rotated during the hardening process; this involves, however, great difliculty, particularly when heavy wheels are hardened. Moreover, both methods involve a relatively lengthy process.

These drawbacks are avoided when the device herein described is applied. The characteristic feature of the present invention resides in the L0 use of two burners both of which begin their path in the middle of the periphery of the double helical gear and are moved with the required velocity from the middle to the respective edge of the wheel. The heated wheel is then quenched in the usual manner. A method is already known by which two burners are used. The object in that case is, however, not that of the present invention. On the contrary, the burners in that case are for simultaneously heating the 'two flanks of a tooth for the purpose of avoiding an irregular hardening of the tooth. In the present invention the two burners are moved in different directions.

5 The invention is diagrammatically illustrated by way of example in the accompanying drawing, in which I Fig. 1 is an elevation,

Fig. 2 is 'a plan,

Fig. 3 is a side view of the device with one sinis gle cam plate,

Fig. 3a is an elevation of the cam plate illustrated in Fig. 3 in cross section,

Fig. 4 is a side view of a modified form of the device having two cam plates separated from each 10 other, and

Fig. 5 is an elevation showing a suitable means for mechanically interconnecting the two burner carriages. 1

For the movement of the burners 10 from the 15 middle of the periphery to the outer edges of the toothed wheel z to be hardened two burner carriages g are provided, the one for the movement to the right and the other for the movement to the left. Each carriage carries a burner it. Both 20 carriages 9 move on the under carriage n which for its part is driven on the frame 0. Both carriages g are driven by the motor m by means of the shaft 1' the toothing of which is formed in such a manner that one carriage is forced al- 25 ways to move in the opposite direction to the other carriage. 4 In order to guide the burner in a perfect manner and in exact agreement with the shape of the tooth, the burner carriers d have guide wheels 01 and 02 which move on earn 0 plates b corresponding with the shape of the teeth of the gear 2 so that the two burners k are always moved exactly parallel to the tooth flanks. For this purpose the carriers (1 are mounted so as to slide vertically in sleeves e on the carriages- 35 g. The guide wheels 01 are kept engaged with the cam plates b by the weight of the burner carriers whereas the guide wheels C2 are kept in continuous contact with the cam plates by means of springs it.v Both burners k may thereby always exactly follow the shape, of the teeth. A sure guiding along the cam plate can likewise be attained by magnetic pressure. In the form of the device illustrated in Fig. 4 two cam plates in and 122 are used for guiding the burners k. The guide wheel 01 runs in contact with the cam plate b1. This cam and guide wheel control theelevation of the burner according to the form of the cam plates. The cam plate b: is fastened to the under carriage n and cooperates with the guide wheel 02. The guide wheel or is kept engaged with the cam plate I): with the aid of the springs in in such a manner that according to the shape of the cam plate, which for its part corresponds with the shape of the tooth flank,

t "e burner is moved along the tooth flank in such a manner that the burner is maintained at the since they would only obscure the interconnect-.

ing means. As shown the interconnecting means comprises racks p and 1" attached to the carriages g, g. Between the carriages a pinion q is mounted on a bracket s and in position to engage the racks p and T. It is clear that movement of the carriage g and the rack r to the right causes rotation of the pinion q which in turn moves the rack p aifixed to the other carriage to the left. It is to be understood that this means is intended to be merely illustrative since other and equally effective means for imparting the desired movement will readily occur to any skilled mechanic.

I claim:

1. Apparatus for surface hardening teeth of double helical gears by heating them by means of the blow-pipe flame which comprises a pair of burners mounted adjacent the gear to be hardened, mechanically driven carriages movable essentially in the direction of the axis of the gear to be hardened carrying supporting means for said burners, means coacting with the burner supports for guiding the burners in predetermined paths and means for simultaneously moving the carriages in opposite directions in such a manner as to move the burners along a tooth from the middle line of the periphery of the gear to the respective edges thereof.

2. Apparatus for surface hardening teeth of double helical gears by heating them by means of the blow-pipe flame which comprises a pair of burners mounted adjacent the gear to be hardened, mechanically driven carriages movable essentially in the direction of the axis of the gear to be hardened carrying supporting means for said burners, means coacting with the burner supports for guiding the burners in predetermined paths and means for moving a first carriage so that the burner mounted on this carriage moves along a tooth from the middle line of the periphery of the gear to the edge thereof, and means for coupling the said first carriage with the other carriage so that when the first carriage moves as described, the other carriage moves in the opposite direction thereby moving the burner mounted on said second carriage along a tooth from the middle line of the periphery of the gear to the opposite edge of the gear.

3. Apparatus for surface hardening teeth of double helical gears by heating them by means of the blow-pipe flame which comprises a pair of burners mounted in front of the gear to be hardened, mechanically driven carriages supporting said burners and movable essentially in the direction of the axis of the gear to be hardened and means for simultaneously moving the carriages in opposite directions in order to move the burners along a tooth from the middle line of the periphery of the gear to the respective edges thereof, and cam. means for guiding each burner in exact alignment with the tooth of the gear.

HERMANN HOLLER. 

